1. Field of the Invention
The present invention relates generally to a recording apparatus for performing a record on, e.g., a consecutive sheet and, more particularly, to an ink jet type consecutive sheet recording apparatus for effecting a print by discharging out an ink.
2. Related Background Art
A wire dot type recording apparatus has hitherto been dominant among recording apparatuses for performing a record on a consecutive sheet. In recent years, however, an ink jet type consecutive sheet recording apparatus downsized but producing less recording noise has been also developed.
Further, the recording apparatus for personal use is requested to be of high recording quality. This recording quality is determined depending on factors such as an image density, an unevenness in density and a sharpness of image. In an ink jet recording apparatus, however, the image sharpness tends to become a subject of discussion. The following is a reason for this.
According to an ink jet recording system, the recording head is formed with a multiplicity of ink discharging nozzles in a direction orthogonal to the feeding direction of the recording medium, thereby discharging the inks at right angle to the surface of the recording medium. However, there is caused no problem if the inks are discharged in the same direction out of all the nozzles. As a matter of fact, there are deviations in terms of directions of discharging the inks out of the respective nozzles.
For example, as illustrated in FIG. 7, the inks should be discharged originally in a direction indicated by an arrowed dotted-line. In fact, however, there are some nozzles from which the inks are discharged in a direction indicated by an arrowed solid-line. In this case, an actual ink reaching point Q deviates by a distance L.sub.1 from an original ink reaching point P, wherein D.sub.1 is the interval between an ink discharging surface 58 of a recording head 57 and a recording medium 53.
Because of this deviation, the image sharpness and the recording quality deteriorate. The above deviation increases (distance L.sub.2) in proportion to an increase in the interval (e.g., interval D.sub.2) between the ink discharging surface 58 and the recording medium 53.
Further, the above problem may be derived from a difference between ink discharging speeds in addition to the deviation between the directions in which the inks are discharged out of the nozzles as the case may be. For instance, the ink droplets discharged out of the nozzles are classified from a larger size into a main droplet, a satellite and a microdot, but discharging speeds of these ink droplets are different.
Therefore, FIG. 8 illustrates the discharging directions in a case where the discharging speeds are V.sub.1 and V.sub.2 (V.sub.1 &lt;V.sub.2), and the discharging direction in the case of the discharging speed V.sub.1 goes as indicated by an arrowed solid line, while the discharging direction in the case of the discharging speed V.sub.2 goes as indicated by an arrowed broken line as a result of being synthesized with a moving speed component V.sub.H of the recording head 57. Thus, the respective discharging directions are different, and, hence, the image sharpness is poor. Then, the above deviation increases in proportion to a magnitude of the interval between the ink discharging surface 58 and the recording medium 53.
Accordingly, it is required that the interval between the ink discharging surface and the recording medium be as small as possible in order to enhance the recording quality in the ink jet recording apparatus.
As illustrated in FIG. 9, however, when the recording medium 53 is a consecutive sheet 53' in which sheet elements are folded alternately sheet by sheet along each score line, the sheet is guided by a tractor 51 of a recording apparatus 50 to a sheet feed roller 52, thus effecting a record. Herein, FIG. 9 is a sectional view showing a case where recording is performed on the consecutive sheet 53' by the conventional ink jet recording apparatus (push type).
In this instance, the consecutive sheet 53' was folded and resultantly formed concave/convex portions shown by numerals 54, 55. Especially, the portion 54 passes through the sheet feed roller 52 and is guided by a platen 56. Then, when recorded by the recording head 57, the portion 54 turns out a convex portion (herein referred to as a convex portion 54) protruding on the side of an ink discharging surface 58 of the recording head 57. In this state, when trying to reduce an interval between the ink discharging surface 58 and the consecutive sheet 53', the consecutive sheet 53' contacts the ink discharging surface 58, resulting in such problems that a recording surface of the consecutive sheet 53' is contaminated, and an ill-discharged state of the ink is produced because paper powders are adhered to an ink discharging port. Further, the same problems are also caused if the interval between the recording surface and the ink discharging surface is small with respect to the portion 55 (herein called a concave portion 55) in which the sheet is concaved on the side of the ink discharging surface 58.